Toyne, Simon. Sanctus

A cassocked monk stands on a mountaintop. Arms outstretched, he forms a tau, the 19th letter of the Greek alphabet. Having escaped from within a cloistered Vatican-like chuch city compound called the Citadel, carved out of a mountain near the fictional Turkish city of Ruin, the escaped monk attracts media attention as he deliberately throws himself off the mountain. Brother Samuel, the escaped monk, knew a secret…a secret the monks of the Citadel have been protecting for thousands of years.

Now Liv Adamsen, an American journalist, learns that her phone number, carved into a small leather strap, has been found inside Samuel's stomach. It turns out Brother Samuel was her long-missing and presumed dead twin brother. When she travels to Turkey to claim his remains, she finds herself the focus of three separate groups...the monks of the Citadel, who wish to cleanse the outside world of any hint of their secret; members of an equally ancient group known as the Mala, who believe Liv and her brother are the ones prophesied to break the Citadel's reign; and the police, who simply want to solve the strange mystery of her brother's very public suicide. Enmeshed in intrigue, it isn’t long before she discovers that the monks of the Citadel will go to any length to protect their mysterious secret, known as the Sacrament, from the world...and the Mala will go to any lengths to expose that secret.

Though it draws the inevitable comparisons to Dan Brown, “Sanctus” is nevertheless a well-developed, entirely unique, and exciting debut with well-rounded characters and a plot that remains grounded despite the potential for hyperbole. I couldn't put it down!